SAN JOSE, Calif. -- No matter where they play, no matter where they practice, no matter the weather, there are two voices that ring above all others during the California football team's spring practice sessions. One has been in Berkeley more than a decade, and another is just coming back. Both running backs coach Ron Gould and wide receivers coach Eric Kiesau have faced big challenges as the Bears pass the two-thirds mark of spring ball, but neither has let up in either the enthusiasm or the intensity department.

"They're still improving, but they have a long ways to go," said Gould after Saturday's open practice at Valley Christian High. "Every week, they're getting better and better, but we're a long ways from where we need to be."

The consummate perfectionist, it is a rare day when Gould is not hoarse after a practice, as he puts the Cal tailbacks and fullbacks to the fire. Gould's relentless hounding of his charges will prove that much more important this season, as there is no tailback currently on the roster in the mold of either Shane Vereen or Jahvid Best.

"We've been blessed with some tremendous, great athletes, great kids. We've got good kids in the program now, and they just need to improve and show that hunger, but we're going to be OK," Gould said. "The guys are working hard and we haven't progressed to the state that we should be at, but the guys are working hard, and we'll get there."

At the moment, the No. 1 back is junior Isi Sofele, who had seven carries for minus-6 yards, though that number includes pouncing on a botched pitch from quarterback Zach Maynard for a loss of 13 yards. Sofele is the clear leader of the pack right now, but once early-enrollee Darren Ervin fully recovers from a sprained ankle and 2011 signees Daniel Lasco and Brendon Bigelow show up in the fall, there could be some heated competition.

"You have to see, when Lasco and Bigelow show up. We know what Isi can do, pretty much," said head coach Jeff Tedford. "Mike Manuel has done a really nice job. He's been a real pleasant surprise, and Covaughn (DeBoskie-Johnson) -- depending on what happens with when Ervin gets back healthy and Lasco gets here and Bigelow gets here, they'll be players, so we're going to depend on some of the young guys, like we did when Jahvid was a freshman and when Marshawn was a freshman. Marshawn was J.J.'s backup and Jahvid played right away as a freshman. Some of these guys coming in are going to have to play."

Run blocking was spotty at times, but Sofele got some tough yards early, gaining 12 yards on his first four carries. Sofele appeared hesitant at times before planting his foot, and had trouble going north-south against a stout defensive line that had 11 tackles for loss, including five sacks.

"They've got to set a block, they've got to be able to get between the tackles, they've got to be able to get outside and it's that whole combination -- we're looking for complete backs: not the ones that just can catch it, not the ones that just can run it, but the ones that can protect, catch it and run," Gould said. "We're always pushing for more. There are expectations that our group has got to play to, and the players understand that. The bar is high, it's always going to be high, and we've all got to come up to that bar. Right now, we're not good enough."

The Bears spread 24 carries over seven players, with the most prolific proving to be junior Covaughn DeBoskie-Johnson. DeBoskie-Johnson ran for 29 yards on eight carries, scoring two touchdowns. His biggest run of the day was a bounce outside to the right for a 16-yard gain. His first scoring trot was a six-yard scamper over right guard during 11-on-11s, and his second came on a five-yard run during goal-line situations.

While DeBoskie-Johnson has gained weight during the offseason, that added bulk helped him at times at the point of contact. On one pitch to the right from senior quarterback Brock Mansion, DeBoskie-Johnson broke several tackles before being upended by safety C.J. Moncrease on the right sideline for a gain of four, which was followed by a physical seven-yard run from fullback John Tyndall, who also had a reception for one yard earlier in the day.

Though he only had two carries, junior transfer Mike Manuel flashed on Saturday, showing poise after coughing up a fumble on a big hit by redshirt freshman Gabe King which was scooped up and taken to the house by Tyre Ellison. On the very next series, Manuel hit the hole in the middle and punched through to the secondary for a gain of 11.

"He's learning. He's doing a great job. I've been very impressed with how he's progressing," Gould said. "He's got a tremendous amount of vision, he's got great balance. That's the thing that people don't understand about him; they try to tackle him and he's got a tremendous amount of balance and he's stronger than people think. That's what separates him from a lot of the guys."

Throughout the spring, Manuel has been quite adept at avoiding contact at the line, freeing him up to pick up big chunks once he gets into the second level.

Fullback Eric Stevens flashed several times on Saturday, particularly on a short five-yard pass from Maynard that the 6-foot, 230-pound junior turned into a 15-yard gain thanks to a gutsy lower-the-shoulder run after the catch.

In all, eight different players caught passes on Saturday for a total of 18 catches, three touchdowns and 195 total yards.

"I think they've responded well," Kiesau said. "I think they're a young group that's got a lot of potential and I've got to try and pull that potential out of them. There's definitely something to work with, with them, and I'm very fortunate to step into a group that I've inherited. So far, it's gone well, but I think we still have a long way to go. There are still a lot of the fine details -- they know the concept of what we're doing, but now we've got to get them honed in on the details to make that next jump. It's a good start, but we have a long way to go."

Kiesau -- in his second stint with the Bears after ascending to the offensive coordinator position at new Pac-12 foe Colorado -- isn't dealing with the type of question marks that Gould has to manage, but he has plenty to think about, anyway, particularly with the loss of touted 2010 recruit Tevin Carter a week ago.

"It's always unfortunate to lose a player, but everybody leaves for different, personal reasons and they have to do what they have to do," Kiesau said. "As a football team, as an offense, we'll move forward and we'll find guys to step up, and that's why you recruit a lot of guys. It's giving other guys some more opportunities to play and we'll get someone ready."

But while Carter is gone, his roommate Kaelin Clay has emerged as one of the top receivers in camp, hauling in three passes for 58 yards on Saturday.

"It was tough to see Tevin leave. We knew each other from a while back, running track back home in Southern California, so I didn't want to see him leave," Clay said. "He's a real close friend of mine, but I wish him the best of luck. I know he's going to do well. I believe in him, and I still stay in contact with him. He's a little brother to me.

"He had told us a couple of times that he was like, 'I don't know if this is the place,' but he stuck it out as long as he could, so I guess it was a ticking time bomb, and it just went off. I miss him, because he was our roommate, so the first day he left, it was kind of hard, but some things you've just got to adjust to and keep the bus moving."

Carter's departure, though, has opened things up for the rest of the wide outs, with both Clay and senior Michael Calvin making the biggest moves lately.

"He's got a very quick step," Kiesau said of Clay. "He gets that ball on the first step and he'll make a guy miss. He'll make that guy miss and get a few extra yards, or like in last week's scrimmage, he'll barrel in near the five-yard line and lean his way forward. For a little guy, he's tough, and that's encouraging to see. He's not scared. I'm excited about him, and I'm excited about the whole group."

Clay showed off perhaps one of the more impressive bursts of the entire corps on several plays, and made a leaping, acrobatic catch on a deep throw from sophomore quarterback Allan Bridgford. Only Clay's initial misjudgment of the ball in flight took away a sure TD strike, but overall, Clay showed a lot of maturity in making mid-route and mid-air adjustments. The redshirt freshman proved to have the best chemistry with Bridgford, who found Clay on a perfectly-thrown touch ball for 14 yards on the left sideline during 11-on-11s in the middle segment of practice.

Bridgford looked to Clay again two plays later, dropping back from the 37-yard line and rolling to his left, throwing across his body and falling short of Clay at the 15. On the very next play, Bridgford delivered perhaps the best throw of the day from any of the quarterbacks. Clay accelerated through a post pattern and past defensive back Adrian Lee , but saw the pass go right through his hands in the end zone.

"The sky is the limit with him," Kiesau said of Clay. "He's got to hone in on the details. He knows, on a flag route, he's getting to X yards and breaking out, and now, it's the details: how you separate. You've seen him do that in the last couple practices. To use that speed to his advantage, you've got to use the details. We've got a ton of film study, watching one-on-ones, watching every rep to get these guys to understand the difference between a good rep and a great rep. That will come with time. He's still very young."

The sophomore signal-caller also had two big tosses to Calvin, starting with a 21-yard hook up on a crossing route, where a blanketed Calvin vaulted into the air to haul in the reception. Calvin recorded 37 yards and a touchdown on two receptions, with the scoring strike coming on a corner route to the back left corner of the end zone from Bridgford, who put just the perfect amount of fade on the toss for a 15-yard score.

"Mike Calvin's a guy, who, when I first got here, there were a couple guys that I pegged as wanting to get more out of, and he was one of them," Kiesau said. "I like the progress he's made, and for him, he's just got to play fast on every down. I tell him that every day, every time he's out there: 'You need to go 100 percent every time,' because his body is so long and so lean and he's got that stride where he can threaten DBs and get them out of their backpedal, and he needs to use that to his advantage. I think, slowly, we're getting that out of him. Now, it's just more that he's got to be consistent and do it every day."

Senior Marvin Jones caught the most balls on the day, hauling in five passes for a total of 23 yards. Jones was very physical at times, flashing late in practice during red-zone drills. Jones took a short pass from Mansion at the 10-yard line and shed a hard hit by cornerback Vachel Samuels to get down to the 6-yard line for a 14-yard reception.

"I'm trying to get every guy here to reach his full potential," Kiesau said. "Keenan Allen's full potential is different from Kaelin Clay's. Kaelin Clay's full potential is very different than Jackson Bouza's. My job is to get all these guys to reach their full potential, and then you have a good collective group."

Kiesau is not only responsible for the wide receivers, but the entire passing game. His corps are really just half of the equation, especially considering the uncertainty at quarterback. Kiesau has made sure to keep his charges within themselves, regardless of who's slinging from under center.

"All we concentrate on is us," Kiesau said. "We just focus on our group, the routes we're running, being at the correct depth, all the details in the route and I'm very confident that Coach Tedford will get the quarterbacks right, and it's a work-in-progress there, too. There are some new guys throwing the ball to the wide outs out there, and we've got to get on the same page with the timing. That's what practice is for, and that's why we're out here. We have some time to do it, so we'll be fine."

Coming off of a disappointing 5-7 season, one of the first things that Kiesau has hammered into his receivers is toughness.

"What we've talked about is that our group, we need to get our edge back," Kiesau said. "We have to have our swagger and we need to carry ourselves, but we can't do it and not perform. A lot of guys will talk a game, but if they don't have it, you can't back it up. You just walk quietly and carry a big sword, you play hard, make plays and your swagger will come."

Kiesau's take on the Teddy Roosevelt bromide certainly has a bit more edge to it -- literally.

"We are getting a little more violent," Kiesau said, "there's no doubt about it."